The prior art is replete with piston ring sealing constructions as is evidenced by U.S. Pat. Nos. 4,185,842; 4,206,930; 3,751,047; and, 4,111,438.
While all of the above mentioned prior art structures are adequate for their intended purposes, they are deficient in a number of regards.
Basically, the pistons in most internal combustion enginges have two, or in some models, three compression rings that fit in grooves around the piston and hold constant tension against the cylinder wall, to prevent the loss of power and compression by "blow by". The open ends of the rings are cut square and gauged for the proper clearance to allow for expansion due to heat, so when the engine is at running temperature, they make a perfect fit around the cylinder wall. This method works quite well in a new or properly reconditioned engine. Unfortunately, as the engine is used, the normal wear on both the rings and the cylinder wall causes a wider gap between the ends of the rings. The rings normally still will have perfect contact with the cylinder wall, except for the hole straight through each ring and this gap keeps getting wider as the engine is used. This is where the "blow by" occurs. It also causes excessive oil consumption and dirty spark plugs, valves, and oil. The oil ring is then subsequently seized in its groove by carbon caused by the product of combustion getting by the compression rings and causing excess heat at the oil ring. Burned oil is simply baked on until the ring can't function properly. If the "blow by" problem is solved, the oil ring will function properly and need not be redesigned. At this point, there is usually nothing else wrong with the engine, but it gets a major overhaul because it has to be completely disassembled to put in new rings.
With the foregoing problems in mind, it became fairly apparent that improvements were necessary in the prior art constructions to produce a piston ring sealing arrangement with improved performance characteristics and none of the problems enumerated above.